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1
50
51 package org.apache.excalibur.configuration.merged;
52
53 import java.util.HashSet  ;
54 import java.util.Set ;
55
56 import org.apache.avalon.framework.configuration.Configuration;
57 import org.apache.avalon.framework.configuration.ConfigurationException;
58 import org.apache.avalon.framework.configuration.DefaultConfiguration;
59 import org.apache.excalibur.configuration.ConfigurationUtil;
60
61
82 public class ConfigurationMerger
83 {
84
94 public static Configuration merge( final Configuration layer, final Configuration base )
95 throws ConfigurationException
96 {
97 final DefaultConfiguration merged =
98 new DefaultConfiguration( base.getName(),
99 "Merged [layer: " + layer.getLocation()
100 + ", base: " + base.getLocation() + "]" );
101
102 copyAttributes( base, merged );
103 copyAttributes( layer, merged );
104
105 mergeChildren( layer, base, merged );
106
107 merged.setValue( getValue( layer, base ) );
108 merged.makeReadOnly();
109
110 return merged;
111 }
112
113 private static void mergeChildren( final Configuration layer,
114 final Configuration base,
115 final DefaultConfiguration merged )
116 throws ConfigurationException
117 {
118 final Configuration[] lc = layer.getChildren();
119 final Configuration[] bc = base.getChildren();
120 final Set baseUsed = new HashSet ();
121
122 for( int i = 0; i < lc.length; i++ )
123 {
124 final Configuration mergeWith = getMergePartner( lc[ i ], layer, base );
125
126 if( null == mergeWith )
127 {
128 merged.addChild( lc[ i ] );
129 }
130 else
131 {
132 merged.addChild( merge( lc[ i ], mergeWith ) );
133
134 baseUsed.add( mergeWith );
135 }
136 }
137
138 for( int i = 0; i < bc.length; i++ )
139 {
140 if( !baseUsed.contains( bc[ i ] ) )
141 {
142 merged.addChild( bc[ i ] );
143 }
144 }
145 }
146
147 private static Configuration getMergePartner( final Configuration toMerge,
148 final Configuration layer,
149 final Configuration base )
150 throws ConfigurationException
151 {
152 if( toMerge.getAttributeAsBoolean( Constants.MERGE_ATTR, false ) )
153 {
154 final String keyAttribute = toMerge.getAttribute( Constants.KEY_ATTR, null );
155 final String keyvalue =
156 keyAttribute == null ? null : toMerge.getAttribute( keyAttribute );
157
158 final Configuration[] layerKids = ConfigurationUtil.match( layer,
159 toMerge.getName(),
160 keyAttribute,
161 keyvalue );
162
163 final Configuration[] baseKids = ConfigurationUtil.match( base,
164 toMerge.getName(),
165 keyAttribute,
166 keyvalue );
167
168 if( layerKids.length == 1 && baseKids.length == 1 )
169 {
170 return baseKids[ 0 ];
171 }
172 else
173 {
174 throw new ConfigurationException( "Unable to merge configuration item, "
175 + "multiple matches on child or base [name: "
176 + toMerge.getName() + "]" );
177 }
178 }
179
180 return null;
181 }
182
183 private static String getValue( final Configuration layer, final Configuration base )
184 {
185 try
186 {
187 return layer.getValue();
188 }
189 catch( ConfigurationException e )
190 {
191 return base.getValue( null );
192 }
193 }
194
195 private static void copyAttributes( final Configuration source,
196 final DefaultConfiguration dest )
197 throws ConfigurationException
198 {
199 final String [] names = source.getAttributeNames();
200
201 for( int i = 0; i < names.length; i++ )
202 {
203 if( !names[ i ].startsWith( Constants.MERGE_METADATA_PREFIX ) )
204 {
205 dest.setAttribute( names[ i ], source.getAttribute( names[ i ] ) );
206 }
207 }
208 }
209 }
210 |
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